Electrocatalytic Reactions

Abstract

Electrocatalysis is defined as the science exploring the rates of electrochemical reactions as a function of the electrode surface properties. The difference between catalytic and non-catalytic reactions is explained. The role of the electrode that does not only accept or supplies electrons (electron transfer), as in simple redox reactions, but also affects the reaction rates interacting with reactants, intermediates, and reaction products is illustrated. Some properties of the main catalytic reactions, viz., hydrogen, oxygen, and chlorine evolution, oxygen reduction, oxidation of small organic molecules suitable for energy conversion (methanol, ethanol, formic acid), and reactions of organic syntheses, are presented. Electrocatalytic reactions involve the strong interactions of reactants and/or intermediates with the electrode surface. As a consequence, the rate of these reactions shows pronounced dependence on the nature of the electrode material. The plots of the catalyst activity (reaction rate) against a descriptor of the adsorption properties such as the adsorption energies or adsorption bond strength of the reactant or reaction intermediates pass through a maximum. These plots are called volcano plots and are generally based on the Sabatier principle.